When one is sitting on a chair or seat, the muscles of the neck must be contracted continuously to maintain the head in an erect position. If the sitting position must be maintained for a prolonged period, this constant strain on the neck muscles causes fatigue and sometimes neck pain. If one tries to relax to avoid this problem, the head will incline or nod, usually forwardly, to one side or the other of the midsagittal plane. When the head reaches the limit of its excursion, the neck strain reoccurs. Also, there may be an involuntary contraction of the neck muscles as they try to return the head to its normal erect position which places an additional strain on the neck that causes muscle soreness and neck pain. Infirm people and invalids who must sit up for prolonged periods in nursing homes and rehabilitation facilities are particulary prone to these problems. So are normal healthy travelers on common carriers.
To help alleviate the aforesaid problems, people place pillows between their heads and the backs of the seats or they tuck pillows between their heads and shoulders to prop up their heads to try to hold their heads in positions most comfortable for themselves. However, such pillows provide only marginal support at best because they tend to conform to the head envelope and they do not provide pressure at those points most calculated to position the head to minimize neck strain.
Because of the unsatisfactory performance of pillows for this purpose, considerable energy has been expended to develop cushions to provide better support for a sitter's head. These prior cushions can be classified by their uses or by the kinds of support that they provide. Most cushions are designed for the reclining, i.e. sleeping or prone, user. However, some of them are designed for the upright, i.e. standing, sitting or semi-reclining, user. Cushions may be calculated to support the head or to support other anatomical parts such as the back, arms or legs. Of those cushions designed for the head, they may support the back of the head, one or both sides of the head or the chin at the front of the head.
Most prior head-support cushions are more or less two dimensional structures relying on the cushion's bulk and compliance to provide the requisite support. That is, most are not shaped to fit human contours. Like the ordinary bed pillow, they possess no particular shape to support the individual's head; rather, they conform to the head outline as noted above. Pillows for reclining individuals are usually shaped to fit the neck and head area either to provide additional support for the neck and head or to provide support while avoiding contact with the user's hair so that they do not disturb the user's hairdo. U.S. Pat. Nos. 3,312,987 and 3,327,330 disclose pillows of that type.
Prior support cushions and pillows for the upright user are designed to support the rear of the head and to provide some lateral support. They were developed under the assumption that the center of gravity of the head lies behind the vertical plane passing through the center of the seventh cervical vertebra so that the weight of the head is borne by the back of the chair or seat. We have found, however, that is assumption is incorrect for two reasons: (1) with few exceptions because most seat backs, including the bench seats in automobiles, do not extend beyond the average person's shoulders. Thus, they actually provide inadequate support for the rear of the head, and (2) with few exceptions, the seats in most forms of conveyance including aircraft and trains do not recline far enough to transfer the weight of the head to the back of the seat. Instead, when the neck muscles relax, the head falls forward to one side or the other of the midsagittal plane.
Those prior pillows and cushions designed specifically to provide head support for a person sitting upright are usually symmetrical and tubular structures which seek to support the head by supporting the back of the neck, usually by filling the gap between the neck and the back of the chair or seat. Examples of such cushions are described in U.S. Pat. Nos. 98,859; 2,328,871; 3,312,987; 3,667,074 and 4,161,794. There are some prior support cushions which are not symmetrical, such as those disclosed in U.S. Pat. Nos. 673,872; 1,787,832; 2,336,707; 2,522,120 and 4,060,863. However, those cushions do not provide adequate support at the back of the head. The last-mentioned patent does provide some neck support on the back 180.degree. of the neck, but this cushion has narrow tapered ends disposed at both sides of the neck so that it does not provide side support for the head.
Other prior pillows approach the problem by providing a cavity or indentation for the neck and head of the user, usually when he is in a reclining position. See U.S. Pat. Nos. 2,880,428 and 3,521,310. Of those cavity-type cushions that are designed for the upright user, the cushion defines a yoke or horseshoe structure which is cumbersome in addition to being unsightly as evident from U.S. Pat. Nos. 2,336,707 and 2,522,120.
In general, those cushions which do adequately inhibit movements of the head in one direction do not adequately support the head against such movements in other directions. For example, the cushion described in U.S. Pat. No. 4,345,347 which incorporates a raised back supports the back of the head adequately, but has small side wings to avoid stifling the user and thereby fails to support the sides of the head effectively. On the other hand, the pillow depicted in U.S. Pat. No. 4,031,578 which does provide adequate lateral head support fails to lend such support at the front and rear of the head.
Thus, to date, to applicants' knowledge, no support cushion exists that provides any support in the front of the head, let alone a combination of the three types of support required to properly support the head of a user reposing in an upright or semi-reclining position. That is, no single prior pillow is able to properly support the rear of the head, the sides of the head at the jawline and, most importantly, the front of the head at the chin. Instead, the prior pillows concentrate on forming a rough contour that permits the head to loll or fall into it. The support from such pillows depends, therefore, on gravity pushing the head to the pillow. Thus, the users of such conventional cushions who are asleep are particularly prone to tossing and lolling which movements tend to awaken them so that they have a fitful rest at best.
Finally, from appearance and marketing standpoints, the prior art cushions, of which the above-identified patented cushions are representative, are generally too large to be practical and so unsightly as to discourage their widespread use on airplanes and other common carriers by captive sitters who would certainly prefer to alight from their flight fully rested and without neck pain.